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Title: Real-time monitoring of the orthohydrogen fraction in a liquid hydrogen moderator

Journal Article · · Nuclear Instruments and Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms
ORCiD logo [1];  [2];  [2];  [2];  [1]
  1. Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Neutron Technologies Division
  2. Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Research Accelerator Division
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Here, we present the first direct measurements of the orthohydrogen fraction in an operating liquid hydrogen moderator loop at a high-powered neutron source. We have developed a Raman immersion probe capable of characterizing the orthohydrogen and parahydrogen makeup of a liquid hydrogen loop approximately every ten seconds, which can see orthohydrogen fractions lower than 0.20 without difficulty. At the Spallation Neutron Source, where the time-averaged power deposition in the studied moderator system is around 0.02 W/cm3, the orthohydrogen fraction increases with beam power and equilibrates at levels of 0.40 and responds to beam trips in a dynamic fashion. Additionally, we find that without deliberate catalyst systems in place, the relaxation due to the piping in the system has insignificant effect in catalyzing the relaxation of freshly condensed hydrogen toward thermodynamic equilibrium, and that the radiation levels associated with activation in a non-operating spallation neutron source target-moderator-reflector assembly likewise has insignificant effect on the liquid hydrogen kinetics.

Research Organization:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE
Grant/Contract Number:
AC05-00OR22725
OSTI ID:
2251598
Alternate ID(s):
OSTI ID: 2228983
Journal Information:
Nuclear Instruments and Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms, Vol. 547; ISSN 0168-583X
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English

References (19)

The conversion of para to orthohydrogen in a gamma-ray and neutron radiation field journal January 1975
Measurements of the change of neutronic performance of a hydrogen moderator at Manuel Lujan Neutron Scattering Center due to conversion from ortho- to para-hydrogen state
  • Ooi, M.; Ino, T.; Muhrer, G.
  • Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 566, Issue 2 https://doi.org/10.1016/j.nima.2006.06.073
journal October 2006
Coupled hydrogen moderator optimization with ortho/para hydrogen ratio
  • Kai, Tetsuya; Harada, Masahide; Teshigawara, Makoto
  • Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 523, Issue 3 https://doi.org/10.1016/j.nima.2003.11.427
journal May 2004
Neutronic studies on decoupled hydrogen moderator for a short-pulse spallation source
  • Harada, Masahide; Watanabe, Noboru; Teshigawara, Makoto
  • Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 539, Issue 1-2 https://doi.org/10.1016/j.nima.2004.10.013
journal February 2005
Measurement of the scattering cross section of slow neutrons on liquid parahydrogen from neutron transmission journal May 2015
Neutronics of a poisoned para-hydrogen moderator for a pulsed spallation neutron source
  • Harada, Masahide; Watanabe, Noboru; Teshigawara, Makoto
  • Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 574, Issue 3 https://doi.org/10.1016/j.nima.2007.01.184
journal May 2007
Experimental verification of equilibrium para-hydrogen levels in hydrogen moderators irradiated by spallation neutrons at J-PARC journal February 2016
Pressure-enhanced ortho-para conversion in solid hydrogen up to 58 GPa journal October 1999
Measured Spectral Brightness of the HFIR Supercritical Hydrogen Cold Source journal July 2008
Ortho-para equilibrium in a liquid D 2 neutron moderator under irradiation journal September 2003
Radiation-Induced Conversion of Liquid Hydrogen journal May 1965
Experimental studies of the effect of the ortho/para ratio on the neutronic performance of a liquid hydrogen moderator for a pulsed neutron source
  • Ooi, Motoki; Ogawa, Hirotatsu; Kamiyama, Takashi
  • Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 659, Issue 1 https://doi.org/10.1016/j.nima.2011.06.098
journal December 2011
The Scattering of Neutrons by Ortho- and Parahydrogen journal August 1937
Future directions for spectroscopy at the Spallation Neutron Source journal July 2019
A liquid hydrogen tube moderator arrangement for SNS second target station journal August 2022
The solid molecular hydrogens in the condensed phase: Fundamentals and static properties journal April 1980
General use of low-dimensional moderators in neutron sources journal May 2018
Study of the Moderators of SNS conference January 2021
Natural ortho-para conversion rate in liquid and gaseous hydrogen journal April 1997

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